How long does it take for blood to spoil? Understanding blood viability

September 29, 2025 •

4 min read

Blood is a perishable, living tissue, and its viability outside the body is limited, even under controlled conditions. The question, "How long does it take for blood to spoil?" is not a simple one, as the answer depends heavily on the blood component and storage method.

Quick Summary

Donated whole blood can typically be stored for up to 35 days, while separated red blood cells can last up to 42 days under strict refrigeration. Platelets, however, are viable for only about five to seven days and require room temperature storage with constant agitation, highlighting the vast differences in shelf-life between blood components.

Key Points

Red Blood Cells Shelf-Life: In a controlled, refrigerated environment, red blood cells can be stored for up to 42 days before they are considered to have "spoiled" or become unusable for transfusion.
Platelets' Short Lifespan: Platelets, another blood component, have a much shorter shelf-life of only 5 to 7 days, as they must be stored at room temperature with constant agitation to remain viable.
Causes of Spoilage: Blood doesn't spoil like food; its viability decreases over time due to a natural process called the "storage lesion," where cells lose function and start to break down.
Impact of Storage Lesion: The degradation of stored blood involves the loss of crucial molecules like ATP and 2,3-DPG, which affects the red blood cells' ability to deliver oxygen to tissues.
Temperature is Key: Incorrect storage temperatures can accelerate blood degradation. Red cells are refrigerated, while other components like platelets have different temperature needs.
Donation Frequency: The limited shelf-life of blood products emphasizes the constant need for new donations to maintain a steady and safe blood supply.

The complex science of blood storage

Blood preservation is a sophisticated process critical to the safety and success of transfusions. Unlike a food product, blood doesn’t “rot” in the conventional sense. Instead, its cells and components gradually degrade and lose their functionality over time, a process known as the “storage lesion.” Proper handling, preservatives, and temperature are all carefully controlled to maximize shelf-life and ensure patient safety.

Factors that influence blood viability

Several factors determine how long blood can be safely stored:

Blood Component: Whole blood is often separated into components like red blood cells, platelets, and plasma. Each component has a different storage requirement and lifespan.
Temperature: The temperature at which blood is stored is paramount. Red blood cells are kept in refrigerators at specific temperatures, while platelets require a different environment.
Preservative Solution: Modern blood storage relies on additive solutions that nourish and stabilize the red blood cells, extending their viability.
Time: Even with optimal storage, the quality and effectiveness of blood components diminish over time. This is why strict expiration dates are enforced.

How long do specific blood components last?


Blood Component	Storage Condition	Maximum Shelf-Life
Red Blood Cells	Refrigerated (1-6°C)	42 days
Whole Blood	Refrigerated (1-6°C)	35 days
Platelets	Room temperature (20-24°C) with constant agitation	5-7 days
Fresh Frozen Plasma (FFP)	Frozen (≤ -18°C)	1 year
Cryoprecipitate	Frozen (≤ -18°C)	1 year

The concept of the “blood storage lesion”

During storage, a number of biochemical and morphological changes occur in red blood cells that reduce their functionality. This is called the storage lesion and is a key reason for the time limits on blood products. The changes include:

Decreased ATP Levels: Adenosine triphosphate (ATP) is the energy source for cells. As ATP levels drop, the red blood cells become more rigid and less effective at transporting oxygen.
Hemolysis: The premature breakdown of red blood cells releases hemoglobin and potassium into the surrounding plasma. Increased hemolysis can be harmful to a transfusion recipient.
Build-up of Potassium: As red blood cells break down, they release potassium, leading to higher levels in the plasma. This can be dangerous for patients with certain medical conditions.
Loss of 2,3-DPG: This molecule helps red blood cells release oxygen to tissues. Levels decrease during storage, which impairs the oxygen-carrying capacity of the blood.
Microvesicle Formation: Red blood cells shed tiny particles called microvesicles as they age, which can cause inflammation in recipients.

The process from donation to transfusion

Collection: Blood is collected from a donor using a sterile procedure and placed into a bag containing an anticoagulant to prevent clotting.
Processing: The whole blood is taken to a lab where it is typically separated into its different components (red cells, platelets, plasma) via centrifugation.
Testing: Each unit of blood is rigorously tested for blood type and infectious diseases to ensure safety.
Storage: The components are stored under precise conditions to maximize their shelf-life.
Transportation: Blood products are transported to hospitals and clinics in insulated containers that maintain the proper temperature.
Transfusion: Before transfusion, the blood is checked again for compatibility with the patient.

Why fresh blood isn’t always best

The idea that fresher blood is always better is a common misconception. Research has shown that in many cases, there is no significant difference in patient outcomes between transfusions of older blood (within its expiry) and fresher blood. The strict storage regulations and protocols developed over decades ensure that even at the end of their shelf-life, blood products are safe and effective for transfusion.

Ethical and logistical considerations

Because of the limited shelf-life, managing the blood supply is a constant balancing act. Blood banks must ensure there is enough blood of all types to meet demand without having excess that will expire and go to waste. Military and civilian shortages present ongoing challenges that drive innovation in extending storage life, as referenced in a study found at the Military Medicine journal website: https://academic.oup.com/milmed/article/189/Supplement_3/560/7671028.

The importance of donating blood

The perishable nature of blood and its components underscores the critical need for regular blood donations. A constant supply is necessary to ensure that blood products are available for surgeries, trauma patients, cancer treatments, and other medical needs. The entire system is dependent on a steady stream of volunteer donors to replenish the supply and replace units as they reach their expiration dates.

Conclusion

While the phrase “blood spoiling” might evoke a vivid image, the reality is a scientific process of cellular degradation. The specific timeline for how long blood remains viable depends on its component, storage temperature, and the presence of preservatives. Red blood cells have the longest shelf-life at up to 42 days, while platelets are much more sensitive. This carefully managed process is a testament to the safety and efficacy of modern transfusion medicine, making regular blood donation a lifeline for countless patients.

Frequently Asked Questions

In medical terms, blood does not 'spoil' like food. Instead, its cellular and functional properties degrade over time, a process known as the 'storage lesion.' This degradation involves the breakdown of red blood cells and loss of their oxygen-carrying capacity, making the blood less effective or even unsafe for transfusion.

To prevent degradation, donated whole blood is typically separated into components. Red blood cells are stored under strict refrigeration (1-6°C), while platelets are stored at room temperature (20-24°C) with agitation. Frozen plasma and cryoprecipitate are stored in freezers for much longer periods.

Platelets have a very short lifespan because they must be stored at room temperature and constantly agitated to remain functional. Their delicate nature makes them susceptible to damage and loss of function more quickly than other components like red blood cells.

Yes, regulatory bodies and extensive research have established strict guidelines for blood product expiration. Blood is considered safe for transfusion up to its expiration date. The effects of the "storage lesion" are monitored and deemed acceptable for clinical use within the specified timeframe.

Expired blood is not simply thrown away. It is often used for other purposes, such as preparing blood products for laboratory use, or for research and development to help improve blood storage and processing techniques.

Studies have been conducted to compare outcomes between transfusing newer versus older blood. The findings are complex, but the consensus among researchers is that, in most cases, transfusing blood stored for longer periods (within the official shelf-life) does not result in significantly worse patient outcomes compared to fresher blood.

Signs of blood degradation, or the storage lesion, are not visible to the naked eye but are measured in a laboratory setting. They include decreased pH levels, increased hemolysis (red blood cell breakdown), and loss of key cellular components that enable oxygen delivery.